1. Field of the Invention
The present invention relates to a fixing device used in an image forming apparatus, such as a copying machine, printer, or facsimile apparatus using the electro-photographic way, and to an image forming apparatus provided with the same.
2. Description of Related Art
Conventionally, a fixing device used in an image forming apparatus comprises a pair of rollers, namely, a heating roller and a pressing roller, arranged inside a box-shaped metal housing constructed by attaching metal stays to a metal frame.
FIG. 35 is a sectional view showing a conventional fixing device 90. In the fixing device 90, a box-shaped metal housing is formed by uniting a lower stay base 91 and an upper stay base 92 of metallic material, as shown by hatched lines, by means of front and rear side plates made of metallic material (not illustrated).
A heating roller 93, a pressing roller 94, and a thermostat 95 and thermistor 96 which constitute a temperature detection sensor for detecting the temperature of the heating roller 93 are arranged inside the metal housing. Furthermore, a guide member 97 for guiding recording paper conveyed into the fixing device 90, a guide member 98 for guiding recording paper conveyed out from the fixing device 90, a separator unit 99 for separating the recording paper from the heating roller 93, a plurality of outer covers 100 made of synthetic resin for covering the outer surface of the metallic housing and the like are mounted on the outside of the metal housing.
However, in this construction, mounting parts are required according to components mounted in the metal housing, which consequently increases the number of parts constituting the fixing device 90. Also, a number of parts are mounted from various directions with respect to the housing, thereby complicating the assembly operation.
Moreover, in such fixing device, the housing is conventionally made to be separable along the path Xxe2x80x94X in FIG. 35 that is the travel route of recording paper to handle paper blockages or jamming and other troubles.
However, in order to achieve positional accuracy of the heating roller 14 and the pressing roller 15 in such a construction, it is necessary to adopt a structure that two parts constituting the housing are firmly connected with each other while being separable. Consequently, it is necessary to use a material having a high strength such as metal and/or to provide reinforcing members in order to assure the necessary strength of the housing.
In view of the above-mentioned problems, it is an object of the present invention to provide a fixing device which assures easier assembly, and an image forming apparatus which is provided with the same.
According to an aspect of the present invention, a fixing device for use in an image forming apparatus in which a toner image is transferred and fixed on recording paper, comprises a housing made of a heat-resistant resin and having an outside surface which constitutes an outside surface of the fixing device. The housing includes a first casing and a second casing which are separable along the conveyance direction of recording paper in the fixing device (i.e., the direction of conveyance of the recording paper in its passage through the fixing device), and a mount section provided on an inside surface thereof for holding a pair of rollers in a predetermined position in the fixing device.
With this construction, since the pair of rollers are both supported in one of the two casings, the housing is not required to be provided in its entirety with the necessary high strength needed to assure the mutual positional registration of the pair of rollers while enabling separation of the housing. Consequently, the housing can be made of heat-resistant resin, while ensuring the required housing strength, and therefore it is possible to achieve a structure in which various components are readily assembled.
The pair of rollers may be supported in one of the casings which thus enables the easy assembling of the fixing device with the pair of rollers are mounted in that casing, and the other casing is thereafter on the first casing.
These and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments/examples with reference to the accompanying drawings.